Datasheet

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AIC36 Control Software

Step 2: Specify the Sample Rate - This is a key design parameter input to the Biquad Tool. The default is

44.1kHz which is the sample rate used on the EVM. The tool will work with any sample rate from 8kHz to

96kHz, however, if a sample rate other than 44.1kHz is selected then the user must go the the clock panel

to modify the PLL and/or clock settings so that the desired sample rate is setup properly when used with

an external audio interface.

Step 3: Specify the Biquad Filters - Select the filter type and subtype and enter any required parameters.

Note that the parameters not used will be grayed out. Use the "Plot" Check-Box to select the filters to plot

and/or download.

Step 4: Calculate the Coefficients - Click on the "Calculate Coefficients" OK button. This calculates all the

selected filters and plots the combined response of all the checked filters. If a filter is not checked it is

treated as an All-Pass filter.

Step 5: Inspect the Plots - Based on the selected filters determine if this is the total desired response.

Also, inspect the Scale (dB) display. Some filters may create a negative gain error which is reflected in the

scale. For example, if the Scale displays 0.5 there is a - 0.5dB gain error which can be corrected in the

analog PGA or the digital Volume. In the last column the stability of the filter is indicated. If the roots of the

filter denominator are less than 1 then the filter is stable and this field will display the text "Stable".

Otherwise, it will display the text "Unstable" meaning that the unstable filter should be re-specified until it is

stable.

Step 6: Download the Coefficients - Click on the "Download Coefficients" OK button. This action will

download the filter coefficients to the device. Note that in order to download coefficients into the device,

the following register writes are done:

1. Page 0 - Select processing block and Power-Down both ADCs

2. Page 4 - Write filter coefficients to both left and right channels as required

3. Page 0 - Power-Up both ADCs

Note that the filter coefficients can be saved as an I2C script by using the Command-Line Interface

Record Button. The I2C commands will be displayed in the Command Buffer which can be selected and

copied to a text command file.

4.1.2.2 DAC Biquad Filter Tool

The DAC Biquad Filter Tool allows the user to specify the following biquad filters downloadable to the

TLV320AIC36:

- All-pass

- High-pass (Butterworth first-order, Butterworth second-order, Bessel second-order, Linkwitz-Riley

second-order, and variable-Q second-order)

- Low-pass (Butterworth first-order, Butterworth second-order, Bessel second-order, Linkwitz-Riley

second-order, and variable-Q second-order)

- EQ (equalizer)

- Notch

- Treble shelf

- Bass shelf

SLAU280A–March 2009–Revised October 2012 TLV320AIC36EVM-K

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